Tuesday, June 14, 2016

When “Public Heath” Isn’t Public

I don’t quite know the meaning of the term “public health.”
Googling the definition hasn’t helped me, because in context its definition is
never consistent. The Google definition is “the health of the population as a
whole, especially as monitored, regulated, and promoted by the state.” Maybe
this vague definition is the right one, because whenever there is some kind of
general health problem (like rising obesity or drug overdoses) the argument for
government intervention always starts with “This is a public health issue!” Notice
that this isn’t really an argument, in the sense that it’s totally circular.

I think “public health” ought to mean something like,
“health issues by which one actor can affect the general health of the
population.” Basically it should be a reference to the effect of a person’s
behavior on *other* people’s health but not his own. This is actually a
radically different definition than the one Google gives and the one that (I
*think*) most people have in mind when they use the term. If I over-eat, or
adopt a dangerous drug habit, or smoke, or skateboard, then it’s not really a
public health issue. In those cases I’m only harming myself. Contrived counterexamples
aside, none of those behaviors significantly affects “the public.” A single
instance of, say, a risky prescription painkiller habit only affects the user.
I don’t think it’s meaningful to count up all the individual instances of
“private health” problems and say that the summation converts it to a “public
health” issue. One person deciding to roll the dice with his own existence is a
private health issue; a thousand (or a million for that matter) doing the same is
*still* a private health issue, just one that many people have in common.

On the other hand, if I drive recklessly, or dump pollutants
into the drinking water supply, or fail to immunize myself or my children, or
if the government implements a policy that makes food or medicine very scarce, these
could legitimately be called public health problems. They are instances of one
party’s behavior affecting another party’s health. Some kinds of intravenous
drug use could also be considered public health issues, considering that these
drug users are extremely prone to blood-borne pathogens that find their way
into their sexual partners or people who share their injection equipment. One
could quibble about how in some of these cases the relevant “public”
voluntarily puts itself at risk and in others it doesn’t, but at least in this
case including the word “public” in “public health” is meaningful.

I recall sitting through a debate on drug legalization. The
person who was pro-legalization finished his argument, and a person behind me
said indignantly to her friends, “He’s ignoring the public health issues.” No,
he was not. He was explicitly arguing that individuals have the right to harm
themselves; they have the right to put whatever chemicals they like into their
own bodies. (He also gave the other standard arguments for drug legalization,
which I won’t list here as I’ve discussed them in detail elsewhere.) He was
arguing, without exactly using my terminology, that there is a difference
between public and private health, and that you don’t convert the former to the
latter just by adding up the instances across a big population. The confused
person behind me was trying to ignore this difference. She was trying to
conflate two different things and paper over the difference by adding the word
“public” to the word “health”. (Perhaps she had in mind that intravenous drug
users infect their partners, in which case I’m being terribly unfair for the
sake of making my point. But this was not the only time I’ve heard “public
health” used in this manner, so I won’t refrain from using this as an example.)

I think there are four different types of health issues that
vary in their degree of public-ness, and they should all be treated separately.
We should drop the term “public health” altogether and explicitly state what
kind of issue we are talking about. The first of the four kinds is the situation in which my
behavior harms myself and no one else (or the harm to others is minimal at any
rate). I dedicated a paragraph to this above, so I won’t belabor the point
here.

The second kind is the situation where I can control my own
exposure to the risk. If I have promiscuous sex or engage in IV drug use with
shared needles, then it’s true that someone can harm me. But I can *decide*
whether I’m exposed to this risk or not. It’s perfectly fair to treat this as a
kind of public health issue, because you may want to know how these kinds of
infections spread and how to stop them. However, we need to keep in mind that
these populations consent to the risks they are taking. Another example is a
polluting factory that is the only source of economic value for a community.
Let’s suppose (not unreasonably) that everyone in the town has the opportunity
to move away if they wish to. Everyone is there of their own volition. Living near a polluting
factory is worth the cost of inhaling pollutants, because you get to work in a
factory or sell goods and services to the factory workers. It may be meaningful
to call the factory a public health hazard, but it needs to be kept in mind
that everyone is better off *with* the factory than *without* it. Also consider
driving. Not reckless driving, but normal driving. There is a non-zero chance
that you will kill someone every time you drive somewhere, but everyone
consents to this risk under the assumption that everyone else obeys various
safe driving practices (obey traffic laws, avoid debilitating drugs, etc.). It
would be great to reduce the risks of these behaviors, but keep in mind that
taking these hazards as a given, people consent to them. People engage in
recreational drug use or normal driving or live near factories because, in
their view, the benefit is worth the risk.

A third kind of health issue is one where you can affect
someone’s health involuntarily. Suppose the IV drug user above doesn’t inform
his wife about his habit and infects her with HIV or hepatitis. Or suppose a
factory agrees to abide by zoning laws and pollution regulations, but then
clandestinely dumps a dangerous dose of pollutants into the water supply. Or
suppose someone drives their car extremely recklessly, perhaps while under the
influence of drugs. It’s fair to say these are all public health issues,
because a party is causing harm to a non-consenting party. These are cases
where the actor who does harm could restrict their contribution to the hazard,
but chooses not to. The harmed party can’t reasonably restrict their exposure
to the hazard. There is a “bad guy” in this story, and it’s fair to sanction
these kinds of behaviors so as to limit the hazard. Moreover, unlike in the
next case I will discuss, sanctioning the hazard-producer *works*.

A fourth kind of health issue, and one that I consider true “public
health”, is the spread of communicable diseases. My case of the IV drug user
above is slightly different, because those were cases where someone can limit
their exposure to the risk *or* their contribution to the risk. There isn’t
necessarily malice or recklessness in this fourth case, as in the case of the polluting
factory or reckless driver. There isn’t necessarily a villain, just normal
people going about their lives within a population exposed to some infection
risk. These are situations where it’s nearly impossible to limit your own
exposure to the risk or your contribution to the risk. The instructions for the
former are “don’t breathe in” and the instructions for the latter are “don’t
breathe out”. Or perhaps there is a less extreme possibility such as “become a
complete shut-in,” but let’s suppose that’s so impractical that it’s not really
an option for most people. These are the situations that truly justify a public
policy. That’s not necessarily to say a government policy. It could take the
form of suggested travel restrictions, rather than mandatory ones. Or a
billionaire purchasing vaccines and giving them away, as Larry Page did for
every child in San Francisco. Never mind that, I’m not going to stand on
libertarian principles here. If ever there is a good case for government
intervention, this is it. There is a true public good/collective action
problem in limiting communicable diseases. The point is not that the travel
restrictions protect the individual who obeys them, or that the vaccines
protect the vaccinated. The point is to disrupt transmission in general. This forth
kind of health issue is one where population effects are important and large. The
one-off bilateral transmissions take a back-seat to these bigger population
effects. There are tipping-points, by which reaching some threshold of infected
people dramatically increases the risk of further infections. There are herd
immunity effects, whereby achieving a certain level of immunization (either
with vaccines or with people surviving prior infections) dramatically reduces
the risk of a pandemic. This is very different in kind from bilateral harms
like “I drive recklessly and hit you with my car” or self-harm like “I engage
in risky drug use and accidentally kill myself.”

Above I have discussed four very different kinds of health issues.
I think we should stop papering over the difference by referring to all of them
as “public health.” These different issues have very different policy
implications. I did once encounter someone who didn’t accept the difference.
He insisted to me that smoking was a public health issue because having friends
who smoke makes it more likely that you will smoke. Smoking, in this framing,
is more like a communicable disease and less like a choice. I don’t buy his
framing of this particular issue, but I won’t discuss it in detail because that’s
not the argument I’m making with this post. I simply want to acknowledge that these four
categories might overlap somewhat and that it might be ambiguous which category
is appropriate for a given issue. We should be explicitly talking about which
category applies. And that’s exactly the discussion that people are dodging
when they promiscuously recite the magic words “public health.” I think people
just lazily use this term when they want the government to do something about
the problem, because “public” sounds like it means it’s happening to all of us.
That’s not right. The “public” in “public health” often just means “I counted
up instances of private health problems over an entire population.” Simply
adding one word to another word does not conjure policy implications out of
thin air. That would require making some kind of argument.